Display modes for liquid crystals can roughly be divided into a vertical electric field mode and a horizontal electric field mode. As for the horizontal electric field mode, there are an In-Plane-Switching (IPS) mode, a Fringe Field Switching (FFS) mode, and etc.
The structure of an existing vertical electric field mode liquid crystal display device is shown in FIG. 1, and from bottom to top, the structure comprises: a backlight source 60, a first polarizer 71, a first substrate (TFT array substrate) 70, a first electrode layer 72, a first alignment layer 73, a liquid crystal layer 90, a second alignment layer 83, a second electrode layer 82, a second substrate (i.e., color filter substrate) 80, a second polarizer 81. In addition, it further comprises a plurality of spacers 100 located between the first substrate and the second substrate.
A transflective liquid crystal display device is to divide each of an existing sub-pixel area into two parts (see FIG. 2, FIG. 3): a transmissive area and a reflective area. Based on whether the thickness of a liquid crystal cell in the transmissive area is the same as that in the reflective area or not, the transflective liquid crystal display device may be divided into two kinds. FIG. 2 illustrates a display mode that the thicknesses of a liquid crystal cell both in the reflective area and in the transmissive area are uniform (both are λ/2). FIG. 3 illustrates a display mode that the thickness of a liquid crystal cell in the reflective area (λ/4) is half of the thickness of the liquid crystal cell in the transmissive area (λ/2). Each of FIG. 2 and FIG. 3 only illustrate a cross section of one pixel. Herein, λ refers to wavelength. The transflective liquid crystal display device of FIG. 2 comprises: an upper polarizer 101, an upper glass substrate 102, liquid crystals 103, an upper λ/4 plate 104, a lower glass substrate 105, a lower λ/4 plate 106, and a lower polarizer 107; and the transflective liquid crystal display device of FIG. 3 comprises: an upper polarizer 201, an upper λ/2 plate 202, an upper glass substrate 203, liquid crystals 204, a lower glass substrate 205, a lower λ/2 plate 206, and a lower polarizer 207.
This structure of the transilective liquid crystal display device suffers from the drawbacks: in the transmissive mode, aperture ratio is decreased, and meanwhile display properties are lowered; in the reflective mode, what is realized by a liquid crystal layer is to modulate environmental light which enters the liquid crystal cell after passing through the upper polarizer and a color filter substrate, and therefore available contrast is limited, and image resolution is insufficient. Further, it is difficult to realize that a good display effect is obtained in each of the two modes, and the fabrication process is complicated.